The first table (image) in this post https://gathering.tweakers.net/forum/list_messages/1735517 https://gathering.tweakers.net/forum/list_messages/1735517 shows

The first table (image) in this post https://gathering.tweakers.net/forum/list_messages/1735517 https://gathering.tweakers.net/forum/list_messages/1735517 shows this issue. It's in Dutch, but the most important columns are the first (gross income), the second to last (net income, including benefits) and the last (effective tax rate on the 1000 gross income increase). Note the last column tells us that making 1000 gross extra will increase your net income about 100 between 32K and 31K gross income. Going from 31K to 32K will even make you lose money.